Determine if Alpha Channel is Used in an Image

. For #2 though, other than looping through every single pixel, is there a simple way I can determine if at least one of the pixels has an alpha channel that is used (i.e. set to some other value than

255

)? All I need back is a boolean and then I'll make determination as to whether to save it out to 32-bit or 24-bit.

UPDATE: I have discovered that ImageFlags.HasTranslucent should provide me with what I'm looking for - unfortunately, it doesn't work at all. For example, PNGs with pixel formats that have at least alpha channel of 66 (semi-transparent) continue to report

False

(Usage:

if((img.Flags & ImageFlags.HasTranslucent) == 4) ...;

). I've tested on all types of images, including .bmp that have an alpha value >0 and <255 and it still reports

You don't have to loop through every pixel (well you might, but it depends on the image). Set up to loop over all the pixels, but just break out of the loop when you find an alpha value other than 255 use the following pseudo code: